Unsaturated fatty acids alter aqueous humor dynamics and uveal flow

We report the effects of four unsaturated fatty acids (UFAs) - arachidonic (AA), linoleic, alpha-linolenic and oleic acid - and one saturated fatty acid (stearic acid) on aqueous humor (AH) dynamics of the isolated arterially perfused cat eye. UFAs, but not stearic acid, increase inflow of AH and elevate IOP; they do not affect the size of the pupil except for AA which produces maximal constriction. Indomethacin blocks the AA induced increase in inflow and the constriction of the pupil but it does not prevent the rise in IOP; indomethacin does not block increased flow or IOP caused by linoleic acid. We conclude that the fatty acid moiety of UFAs affects the blood aqueous barrier and possibly also the outflow channels. AA has a dual effect since in addition to a general fatty acid effect, an AA induced cyclo-oxygenase product affects AH inflow and constricts the pupil. All UFAs dilate the iridial part and constrict the choroidal part of the ciliary processes; this may contribute to increased inflow of AH and elevation of IOP.